The benthic macrofauna of the variable salinity waters ecosystems along the Atlantic coast of tropical Africa; biodiversity variations with the current climatic conditions (rainfall) and the regional climatic history

The West African margino-littoral benthic fauna biodiversity, defined from an exhaustive bibliographical study, is lower in arid (Mauritania, Angola) or subarid climates (Senegambia, from Ghana to Benin) and higher in humid regions (from Guinea-Bissau to Liberia and from Nigeria to Gabon) or in regions with large rivers (Ivory Coast, Congo). Under arid and dry climates, periodical severe conditions (high salinity, anoxia...), dramatically increased during the 1970-1980 decades, are not favourable to the settlement of species and communities, despite the remarkable adaptative response of some species like the bivalve Senilia senilis on the Banc d'Arguin (Mauritania). This situation is also the consequence of Quatemary palaeoclimatic events; during the driest periods, species may have survived in refuges round on the still humid climate coasts, from Guinea to Ivory Coast and from Nigeria to Congo.